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NASA NTRSDate not supplied

Future Improvements to Impact for Long Duration Exploration Spaceflight

BACKGROUND: While NASA currently uses the Integrated Medical Model (IMM) to model spaceflight medical risk for Low Earth Orbit missions, IMPACT (Informing Mission Planning via Analysis of Complex Tradespaces) was created to improve the fidelity of medical risk analysis for exploration missions involving the Lunar surface and beyond. OVERVIEW: While completion work continues on the initial version of the IMPACT tool, work has already begun to investigate ways to further enhance the fidelity of the model and its utility to stakeholders. DISCUSSION: Future additions leveraging the more robust and flexible IMPACT architecture include analyzing mission segments to account for segment-specific environments (ie. Lunar surface or microgravity), clinically tracible outcomes based on partial treatment of conditions, the ability to model mission outcomes based on provider Knowledge, Skills, and Abilities (KSAs), and the ability to affect the incidence of conditions based on the occurrence of related conditions (e.g. UTI progressing to sepsis). IMPACT also enables the addition of new conditions to its database as required to meet future risk assessment needs. Ultimately, the desire is to broaden IMPACT from a tool that models/trades medical risk to one that does so for all crew health and performance relevant systems (e.g., food, exercise, etc.).

E Stratton↗

NASA NTRS2023

Orion Cabin Lighting System: Filter Workaround for Maintaining Crew Circadian Entrainment

Introduction: Suboptimal crew circadian entrainment (CCE) is common and results in cumulative fatigue and reduced cognitive function. This may promote use of psychostimulants and hypnotics. The Orion Cabin Lighting System (OCLS) consists of 15 dimmable lamps circuited to several zones. The OCLS monochromatic white lamp design is insufficient for maintaining CCE. While blue light (480-nm) elicits peak wake-cycle response, it is a powerful disruptor of CCE. We propose OCLS lamp filters (OLFs) as a workaround for maintaining CCE. Methods: Preliminary OLFs testing utilized a tunable-white LED to serve as a baseline lamp in the NASA Lighting Lab’s controlled environment (prototype OCLS lamps were unavailable). Illuminance and spectral irradiances were measured with the NASA Lighting Lab’s spectroradiometer. ConOps is proposed for OLFs. Results: OLFs markedly attenuated 480-nm light and illumination with minimal mass/volume requirements. ConOps includes in-flight deployment of OLFs and reducing OCLS lamp intensity prior to bedtime. Pros: minimal mass/volume, no added power, and a simplistic design. Cons: manual twice-daily articulation of OLFs, undetermined frangibility/flammability/off-gassing and effects on thermal regulation, and untested task illumination or color fidelity in the Orion cabin. Discussion: While OLFs aptly attenuate 480-nm light from our tunable LED lamp in the Lighting Lab’s controlled environment, they remain untested within the Orion cabin on OCLS lamps. Future tests include Orion cabin illumination optimization for appropriate Lux delivery and ensuring task/color fidelity with OLFs deployed. Adequate OCLS cooling should be similarly assessed. Other safety testing includes OLF frangibility/flammability/off-gassing in an enriched-O 2 /hypobaric environment. Together, these data will demonstrate OLFs provide a viable workaround for maintaining CCE further ensuring mission safety and success.

Carlos Rene Dostal↗

NASA NTRSDate not supplied

Validation of Machine Learning Algorithms for Hyperspectral Inversion of Common Water Quality Indicators

The upcoming transition to a diverse suite hyperspectral airborne and orbiting optical sensors will provide an unprecedented opportunity to measure inland water quality characteristics at a fidelity not previously achievable. This presentation will assess prototype deep learning models trained on synthetic hyperspectral data and validated with collocated in-situ measurements. Synthesized data is becoming increasingly popular for use in data-driven approaches to complex problems, and can compliment real data to increase performance on complex and unusual phenomenon, reduce or test bias, and experiment to demonstrate explainability. We will present insights from hyperspectral inversions of Chlorophyl-a, Phycocyanin, and concentration of non-algal particles using selected orbiting and airborne sensors over diverse, optically complex aquatic scenarios. We analyze how various optical water types affect fidelity of results and where improvements can be made as we prototype for globally operational water quality algorithms which can be leveraged by upcoming hyperspectral missions such as the Surface Biology and Geology (SBG) mission.

Surface Biology and Geology (SBG)↗

NASA NTRSDate not supplied

Multihierarchy Gaussian Process Models for Probabilistic Aerodynamic Databases using Uncertain Nominal and Off-Nominal Configuration Data

Probabilistic aerodynamic databases are a crucial component of the development lifecycle for aerospace vehicles. A key challenge when building aerodynamic databases is that most data used to construct them represent various simplifications of the real flight vehicle. For example, wind tunnel models often simplify the vehicle geometry and surface roughness characteristics, while CFD computations often make simplifications to the physics being modeled, such as fully laminar or turbulent calculations. Multifidelity data fusion models rely on a user being able to define a hierarchy of fidelity levels anchored to some "truth" data. This approach is unsatisfactory when no data can be considered to accurately reflect real flight conditions. In this work, we provide an alternative approach by presenting a consistent mathematical framework for building probabilistic aerodynamic databases in the form of a conditional probability distribution described by an ensemble of multifidelity Gaussian Processes. Instead of relying on a single hierarchy of data fidelity levels, the presented framework identifies a "nominal" configuration and potential corrections to the nominal which represent specific physical phenomena not represented in the nominal data. The nominal and correction functions themselves are constructed as multifidelity Gaussian Processes and linearly combined to form an ensemble model which fuses the uncertainties associated nominal and correction models. Results obtained using the proposed framework on a simplified Orion Crew Module wind tunnel dataset demonstrate the predictive capability of the multihierarchy framework. We further demonstrate the benefits of such a probabilistic aerodynamic database approach through function sampling and computing the conditional distributions of derived quantities, such as the trim angle of attack and aerodynamic coefficients at trim.

Gaussian Processes↗

NASA NTRSDate not supplied

JETT3: A Holistic, Integrated Analog for Artemis Lunar Surface Exploration

Since 1972, NASA astronauts have performed hundreds of Extravehicular Activities (EVAs) in support of Skylab, Space Shuttle and International Space Station missions. Not since Apollo, however, have EVAs been driven by discovery-based principles of scientific exploration. Upcoming Artemis missions are challenged to build on lessons learned from Apollo, merging 50 years of EVA experience with the planetary science community’s expertise in the remote surface exploration of Mars. The highest-fidelity preparation for Artemis includes both operational and scientific underpinning to represent the complete, complex picture of lunar surface operations. The Joint EVA & Human Surface Mobility Test Team (JETT) is an interdisciplinary team providing such an environment for collaborative analog testing. JETT builds upon prior analog campaigns (e.g., [1, 2]) to provide high-fidelity environments for hardware and concept of operations development. Sponsored by the NASA EVA & Human Surface Mobility Program (EHP), JETT includes representatives from EHP, NASA Engineering, the Science Mission Directorate (SMD), Human Health & Performance, and the Flight Operations Directorate (FOD). JETT tests evaluate NASA reference designs for EVA (e.g., suits and tools), address gaps and risks for Artemis lunar surface operations, develop capabilities for EVA and science tasks, enable technology maturation, and provide training for Artemis EVA operations. JETT3, the final JETT field test of FY22, occurred Oct 3-11, 2022 in the San Francisco Volcanic Field north of Flagstaff, AZ. The test focused on developing the Artemis concept of operations and systems, including integrating an Artemis-like Science Team into a NASA Flight Control Team (FCT) to plan and execute a series of simulated lunar EVAs in an environment analogous to Artemis 3.

T. E. Caswell↗

NASA NTRSDate not supplied

Tailoring Early Concept Maturity Levels for Small Satellite Missions

The Concept Maturity Level (CML) framework has gained widespread acceptance as a process to assess mission concept maturity, particularly for early mission concepts in the formulation phase. Popularized by the Jet Propulsion Laboratory almost 15 years ago to evaluate large NASA science mission concepts, the CML method offers wide-ranging programmatic and technical evaluation criteria to assess and measure the progress of mission concepts at all stages of maturity. It also provides a useful tool to facilitate stakeholder relationships through effective engagement, interaction, and communication. The CML approach is modeled largely after the widespread Technology Readiness Level (TRL) scale, a measure of how new technology progresses from early concept through to being operational at the mission flight system level. Tailoring the CML framework for small satellites allows for more relevant technical and programmatic evaluations for these missions. Given the diversity of small satellite mission objectives, cost constraints, complexity, and risk tolerance, this modified CML framework enables study teams and stakeholders to determine the appropriate CML fidelity to implement based upon the opportunity and strategic investment approach. A decision process flow method is proposed to guide teams through the logic of determining what CML fidelity to implement in evaluating small satellite mission concepts. The goal is to provide enhanced stakeholder engagement such that CML assessments are clearly articulated and understood early in the design study. This would allow for more appropriate application of CML methodology by study teams developing University led missions, technology demonstrations, commercial constellations, and more complex planetary science missions.

Concept Maturity Level↗

NASA NTRSDate not supplied

Aerothermodynamic Measurements in Hypersonic Non-Equilibrium Flows

High enthalpy arc-jets are unique facilities particularly suited for simulating complex flows in the aerospace field, such as the aerothermodynamics of a re-entry vehicle. Arc-jets are often used to evaluate important design factors such as heat shield materials and vehicle design. Characterization of these facilities is important, as studies often match specific in-flight environments during experiments. Due to the complex environment produced by an arc-jet, with effects such as thermodynamic and chemical non-equilibrium occurring in the flow, characterization experiments are significantly more difficult than in traditional blow-down wind tunnels. The current work aims to characterize an arc-jet facility in terms of flow temperature, velocity and unsteadiness, in a spatially-resolved analysis. To achieve this goal, a non-intrusive imaging technique called “planar laser-induced fluorescence” was performed in the NASA Langley Hypersonic Materials Environ-mental Test System arc-jet facility. The experimental data was analyzed to produce the quantitative measurements in multiple regions of the flow around a blunt body sample. A quasi-1D low fidelity solver was created to numerically simulate the flow to investigate non-equilibrium effects occur-ring outside the imaging region in the arc-jet nozzle. Unsteadiness in the test section was minimized by analyzing a subset of data assessing the gas injection location. Radial velocity, rotational temperature and translational temperature measurements are provided that can be used to validate future high-fidelity computational studies. The temperature measurements revealed rotational non-equilibrium potentially occurring in the flow. This work provides a methodology for characterizing arc-jet facilities, identifying and correcting sources of systematic error, and estimating the uncertainty associated with the quantitative measurements.

laser induced fluorescence↗

NASA NTRSDate not supplied

JETT3: A Holistic, Integrated Analog for Artemis Lunar Surface Exploration

T. E. Caswell↗

NASA NTRSDate not supplied

Toward High-Quality X-59 Sonic Thump Measurements

Brigham Young University has been investigating best practices for recommendation to NASA in upcoming X-59 sonic thump measurements. This preparatory work has focused both on obtaining high-fidelity data and standardizing signal analysis techniques for sonic thumps. Included in the research are topics such as whether to use a ground-based or elevated microphone, how to use low-noise microphones and still recover high-fidelity data at low frequencies, and estimating the uncertainty in a given measurement due to local atmospheric turbulence effects. Also included is a study of windowing techniques, zero padding, and the removal of high-frequency ambient noise contamination.

sonic boom↗

NASA NTRS2023

NDARC - NASA Design and Analysis of Rotorcraft: Theory - Appendix A

The NASA Design and Analysis of Rotorcraft (NDARC) software is an aircraft system analysis tool that supports both conceptual design efforts and technology impact assessments. The principal tasks are to design (or size) a rotorcraft to meet specified requirements, including vertical takeoff and landing(VTOL) operation, and then analyze the performance of the aircraft for a set of conditions. For broad and lasting utility, it is important that the code have the capability to model general rotorcraft configurations, and estimate the performance and weights of advanced rotor concepts. The architecture of the NDARC code accommodates configuration flexibility, a hierarchy of models, and ultimately multidisciplinary design, analysis, and optimization. Initially the software is implemented with low-fidelity models, typically appropriate for the conceptual design environment. An NDARC job consists of one or more cases, each case optionally performing design and analysis tasks. The design task involves sizing the rotorcraft to satisfy specified design conditions and missions. The analysis tasks can include off-design mission performance calculation, flight performance calculation for point operating conditions, and generation of subsystem or component performance maps. For analysis tasks, the aircraft description can come from the sizing task, from a previous case or a previous NDARC job, or be independently generated (typically the description of an existing aircraft). The aircraft consists of a set of components, including fuselage, rotors, wings, tails, and propulsion. For each component, attributes such as performance, drag, and weight can be calculated; and the aircraft attributes are obtained from the sum of the component attributes. Description and analysis of conventional rotorcraft configurations is facilitated, while retaining the capability to model novel and advanced concepts. Specific rotorcraft configurations considered are single-main-rotor and tail-rotor helicopter, tandem helicopter, coaxial helicopter, and tiltrotor. The architecture of the code accommodates addition of new or higher-fidelity attribute models for a component, as well as addition of new components.

NDARC↗

NASA NTRSDate not supplied

An Overview of the Proprotor Performance Test in the 14- by 22-Foot Subsonic Tunnel

This work experimentally investigates the aerodynamic behavior of proprotors across a wide range of angles of attack. These flight conditions are intended to be representative of Urban Air Mobility (UAM) vehicle platforms that utilize articulating propulsors to transition from a vertical takeoff and landing (VTOL) phase typical of a conventional rotorcraft, to an axial mode of forward flight typical of a fixed-wing aircraft. These data are used to identify the potential limits of lower fidelity aerodynamic modeling tools, as well as to inform future acoustic phases of testing. Tests were conducted on two proprotor designs in the NASA Langley 14- by 22-Foot Subsonic Tunnel using an articulating propeller test stand. Hover results identified unique flow physics on one of the proprotors, including severe outboard flow separation and perpendicular blade vortex interactions on the outboard portions of the blades. Transition and forward flight conditions yielded very informative trends in terms of both on- and off-axis forces and moments against which low-fidelity prediction models were compared.

aerodynamics↗

NASA NTRS2023

Computational Study of Vortex-Induced Separation for a 5-Bladed Rotor

This work computationally investigated the rotor blade vortex-induced separation recently observed during an aerodynamic rotor test campaign in the NASA Langley Research Center 14- by 22-Foot Subsonic Tunnel. Two separate approaches (i.e., airfoil modification and blade tip modification) were studied to mitigate the vortex-induced separation. Low-fidelity tools based on blade element momentum theory were shown to mispredict the rotor inflow and were also shown to not capture the vortex-induced separation caused by perpendicular blade-vortex interaction. This misprediction was exploited to isolate the aerodynamic thrust deficit caused by the vortex-induced separation (i.e., 20%) from the thrust deficit due to inflow variation (i.e., 31%). High-fidelity tools were shown to reasonably predict aerodynamic forces within 13% and flow separation when compared to experimental results. The modified airfoil variant of the baseline rotor effectively mitigated the vortex-induced separation while the blade tip modified variant still showed separation, though the size and strength of the vortex was reduced. Acoustic predictions were underpredicted by 10 dB from preliminary measurements taken in the untreated wind tunnel. Broadband noise contributions from different rotor blade sections showed that self-noise due to flow separation and other turbulent boundary layer mechanisms was the dominant noise source for all three rotor cases, followed by blade-wake interaction noise caused by perpendicular blade-vortex interactions.

aerodynamics↗

NASA NTRS2022

Robust Vision-based Multi-spacecraft Guidance Navigation and Control using CNN-based Pose Estimation

In this paper, we present an end-to-end simulation framework for tracking an uncooperative Target spacecraft in Low Earth Orbit using a CubeSat-class Ego spacecraft outfitted with a camera. Currently, capturing high-fidelity realistic images in space for this scenario is difficult and exorbitantly expensive. Therefore, we developed a framework to simulate the spacecraft orbits in Basilisk software and generate high-fidelity realistic images of spacecraft in Unreal Engine, including the effects from Sun, Earth, Moon and stars. The Ego spacecraft uses cameras to capture images of the uncooperative Target and estimates its position and attitude using a CNN based 6DOF pose estimation pipeline, eliminating need for large SWAP-C(Size, Weight, Power and Cost) sensors like LIDAR or reliance on inter-spacecraft communication, This CNN, which is motivated by ESA’s Pose Estimation challenge of 2019, is trained using simulated data from our end-to-end simulation framework. We compare the performance of two distinct CNNbased algorithms for pose estimation along a nominal trajectory. In presence of non-Gaussian modeling uncertainties, the statedependent estimation error is characterized with a quadratic upper-bound. The quadratically-bounded error can be used by a robust controller to maneuver

Rahmani, Amir↗

NASA NTRS2023

Concept Design for a 5 MW Partially Superconducting Generator

This paper presents a concept design for the 5 MW generators on NASA’s SUSAN hybrid electric flight concept. The performance targets for this machine are 25 kW/kg and 99% efficiency. The concept design is a partially superconducting machine that builds on NASA’s past work on its High Efficiency Megawatt Motor (HEMM). A partially superconducting machine design tool is used to create a preliminary concept design capable of achieving the target specifications for the SUSAN generator. Higher fidelity design and analysis is applied to the preliminary design. After high fidelity analysis the machine is predicted to achieve 22.3 kW/kg and 99.1% efficiency. Lessons learned from this concept design will be incorporated in the next iteration of the machine.

Thomas Tallerico↗

NASA NTRS2023

Concept Design of a 5 MW Partially Superconducting Generator

This paper presents a concept design for the 5 MW generators on NASA’s SUSAN electric flight demonstrator concept vehicle. The performance targets for this machine are 25 kW/kg and 99% efficiency. The concept design is a partially superconducting machine that builds on NASA’s past work on its High Efficiency Megawatt Motor(HEMM). A partially superconducting machine design tool is used to create a preliminary concept design capable of achieving the target specifications for the SUSAN generator. Higher fidelity design and analysis is applied to the preliminary design. After high fidelity analysis the machine is predicted to achieve 22.3 kW/kg and 99.1% efficiency. Lessons learned from this concept design will be incorporated in the next iteration of the machine.

Thomas Tallerico↗

NASA NTRS2023

Efficient Calibration of Expensive Computational Models

Accounting for uncertainty when calibrating expensive computational models is a common challenge faced by scientists and engineers. Often Bayesian techniques are adopted to estimate a probability density function over the model parameters given noisy empirical data. The methods used to perform this type of probabilistic calibration are computationally prohibitive in that they require a large number of evaluations of the expensive model. In these cases, surrogate modeling -- that is, using a fast-to-evaluate, lower fidelity stand-in for the original computational model -- may be the only option to alleviate this computational burden. However, the upfront cost of generating training data to build a surrogate model can itself be expensive. As such, it is important to be judicious when selecting training points at which the full-fidelity model is evaluated. Here, an active learning approach is proposed that enables efficient selection of training points using approximate samples of the calibrated parameter probability density function. In this way, the training points can be concentrated in regions where the calibration algorithm requires high model accuracy.

active learning↗

NASA NTRSDate not supplied

Testing the Exploration ConOps (ExCon) Mockup Suit in Lunar Analog Environments in 2022

Understanding how to effectively train for Extravehicular Activities (EVAs) for Artemis missions is critical. Developing high-fidelity simulation environments is important for Artemis mission preparation. Because the actual Lunar exploration environment cannot be fully replicated on Earth, it is paramount to determine where and how to properly train the Artemis team. The overall focus for this test series was developing the capability to perform Artemis simulated EVAs in high-fidelity, full-scale environments. This test series was broken into three distinct tests titled after the EVA & Human Surface Mobility (HSM) Program (EHP) integrated test team: Joint EVA & HSM Test Team (JETT). The test locations are planned to serve as Artemis training sites and were selected because of their relevance to the expected Artemis Lunar terrain. JETT1 was conducted near Kilbourne Hole by El Paso, Texas and focused on hardware development and checkout. JETT2 was conducted in the Icelandic Highlands and began the transition towards EVA concept of operations (con-ops), risks and technology. JETT3 was conducted near SP Crater by Flagstaff, Arizona and focused on simulating the Artemis III mission including a Houston based Flight Control Team (FCT) and a Science Mission Directorate (SMD) science team. All three JETT tests utilized the Exploration Concept of Operations (ExCon) mockup space suit. The ExCon mockup suit is a lightweight, unpressurized Exploration Extravehicular Mobility Unit (xEMU) simulator. While it cannot replicate the feel of working within a pressurized suit, it does introduce similar volume constraints and some of the mobility programing to simulate the user experience in the xEMU. Overall, the JETT testing was able to create a simulated Lunar EVA and have two subjects perform full scale operations in line with Artemis III mission expectations. Future work is planned to continue to improve the simulation quality of Lunar EVA simulations.

spacesuit↗

NASA NTRS2022

Robotics Verification and Validation Strategies for Perseverance Rover Sampling and Caching

The Mars 2020 Sampling and Caching Subsystem(SCS) is the most complex robotic system ever fielded on a MarsRover. It includes a 5 degree-of-freedom Robotic Arm, coringdrill, gas Dust Removal Tool, interfaces for two turret-mountedinstruments, and an Adaptive Caching Assembly (ACA). TheACA is itself a complex robotic system, containing hardware tosupport docking and bit exchange, a 3 degree-of-freedomSample Handling Assembly for manipulating sample tubes,storage for several drill bits and sample tubes, and mechanismsto support observing and sealing samples collected by the drill.To successfully verify and validate the SCS hardware andsoftware and its integration with the Mars 2020 flight systemseveral key strategies were employed.The SCS Verification and Validation (V&V) program utilizedmultiple test venues with tiered levels of fidelity. These includedsimulation and visualization software environments, low fidelitydevelopment testbeds, testbeds with high fidelity SCS hardwareand commercial off-the shelf avionics, integrated systemtestbeds with flight-like avionics, and environmental testbedscapable of simulating Martian surface temperature andpressure. Multiple units of each SCS hardware componentmoved fluidly between test venues to accomplish myriadstandalone and coordinated test objectives. Test preparationand executions were performed by a diverse team of engineerswith training and technical ownership tailored for individualexperience and role. Despite significant differences between testvenues, the SCS V&V team established efficient and consistentprocesses and tools for procedure development, test execution,and data review that enabled personnel, as well as technicalproducts such as sequences and parameter configurations, toflow between venues effectively. A series of benchmark testsprovided evidence of performance consistency as elements weretransferred between venues and as system capability evolved.This paper provides an overview of the SCS V&V program andexplores several overarching strategies that enabled successfuloperation in the face of unprecedented complexity. Keyoutcomes of the SCS validation effort are summarized, alongwith lessons learned and beneficial integrations of validationtool and process innovations into Mars surface operations.

Brooks, Sawyer↗